Electrostatic spray painting method and apparatus



Apnl 19, 1960 L. BECK 2,933,414

ELECTROSTATIC SPRAY PAINTING METHOD AND APPARATUS Filed Jan. 27, 1958INVENTOR.

LOU I S BE C K wadm ATTORNEYS United States atent bra! ELECTROTATICSPRAY PAINTING METHOD AND APPARATUS 7 Louis Beck, Seven Hilis, OhioApplication January 27, 1958, Serial No. 7il,5-:i

tClaims. (Cl. 117-93) This invention relates generally to anelectrostatic spray painting method and apparatus for practicing thesame.

A primary object of the invention is to provide a method ofelectrostatic painting in which the paint is converted into a fog-likevapor or cloud which is espe cially well adapted to be moved in aneflicient manner through the electrostatic zone.

Another object of the invention is to provide a method of electrostaticpainting, in which the paint is utilized in a condition in which it isunmixed with air or other gaseous medium or vehicle, whereby thedifficulties encountered when the paint is so mixed are obviated.

A further object of the invention is to provide a method ofelectrostatic painting, in which novel means,

including a high pressure jet or stream of'paintis used,

in conjunction with a strike plate against which said stream impinges.

Other objects and advantages of the invention will be come apparent inthe course of the following description,

taken in connection with accompanying drawing, which forms a part ofthis application, and in which the single figure illustrates more orless diagrammatically the principal features of the invention.

Referring more particularly to the drawing, reference numeral 1designates a paint container or receptacle, in which paint, unmixed withair or other gaseous vehicle, is subjected to a high pressure, as bymeans of a hydraulic pump or the like, so that the paint is dischargedat a relatively high velocity, through a nozzle 2.

The paint emerges from the nozzle 2 in a straight needle-like stream 3at a velocity such that the stream of paint impinges against a strikeplate 4, which is disposed in the path of the stream, and at an angle tothe stream. The paint impinges upon the strike plate 4 with sufiicientenergy to cause the paint to become atomized by the strike plate, andthe plate directs the atomized paint particles, indicated by referencenumeral 5, towards articles 6, which. are to be coated with the paint.

The articles or work may be conveyed past the atomized paint, as bymeans of a conventional mechanical conveyor, moving in the directionindicated by the arrow.

The atomized paint particles pass through an electrified orelectrostatic zone, which is created between the strike plate 4 and thearticles 6, by making the plate the positive terminal of the zone, andthe articles 6, the negative terminal of this zone. The particles ofpaint are thus attracted to and coat the articles 6. in some cases, thecontainer or receptacle :1 may be included as part of the positiveterminal of the electrified or electrostatic zone.

The paint, as it leaves the strike plate, becomes atomized, forming afog-like vapor, which is exceptionally well adapted to be moved inan-efiicient manner through the electrostatic zone; This results fromthe fact that the particles are well dispersed throughout the vapor orfog, are moving at a relatively low speed, as compared to the speed atwhich they left the nozzle 2, and are unmixed with air or other gaseousmedium, such as is commonly used in propelling paint through nozzles of"ice accounted for by the fact that the force of the stream from thenozzle 2 is expended against the strike plate, and the fog or vaporwhich is created is virtually invisible.

The pressure at which the stream of paint emerges from the nozzle 2 maybe varied, depending upon the size of the passageway through the nozzle,and this pressure may be varied in accordance with the distance of thestrike plate from the nozzle, the size and shape of the strike plate,the distance of the strike plate from the articles to be coated, thestrength of the electrostatic zone or field, the viscosity of the paint,and other factors.

The size and shape of the strike plate may be varied in accordance withthe nature, size and shape of the articles which are to be coated, andit is desirable to so shape the strike plate as to form a paint or fogpattern which conforms to the nature, size and contour or shape of thearticles.

For this purpose, the strike plate may, in some instances, assume aconcave or convex or other shape or form.

It is to be understood that various changes in the method and apparatus,as described, may be made, without departing from the spirit of theinvention or the scope of the appended claims.

Having thus described my invention, I claim:

1. The method of electrostatically painting articles which comprisesprojecting a thin stream of paint substantially free of admixture withair or other gas' and at a high pressure through a nozzle and against astrike plate disposed in the path of the stream but at an angle to saidpath, whereby the paint, after striking the plate is deflected at thepoint of impingement in a direction angular to the direction of saidstream, and is broken up into particles forming a fog-like vapor, andcausing said vapor to pass through an electrostatic zone between saidstrike plate and said articles, to coat said articles.

2. The method, as defined in claim 1, in which the electrostatic zone iscreated by making the strike plate one terminal of a high potentialcircuit, and the articles the other terminal of said circuit.

3. The method, as defined in claim 2, .in which the articles areconveyed past said electrostatic zone.

4. The method of electrostatically painting articles which comprisesprojecting a thin stream of paint sub stantially free of admixture withair or other gas and at a high pressure through a nozzle and against astrike plate disposed in the path of the stream but at an angle to saidpath and being stationary with respect to said nozzle, whereby thepaint, after striking the plate is defiec'ted at the point ofimpingement in a direction angular to the direction of said stream, andis broken up into particles forming a fog-like vapor, and causing saidvapor to pass through an electrostatic zone between said strike plateand said articles, to coat said articles.

5. The method of painting articles which comprises projecting a thinstream of paint substantially free of admixture with air or other gasand at a high pressure through a nozzle and against a strike platedisposed in the path of the stream but at an angle to said path, wherebythe paint, after striking the plate is deflected at the point ofimpingement in a direction angular to the direction of said stream, andis broken up into particles, which are directed to coat said articles.

References Cited in the file of this patent UNITED STATES PATENTS2,684,656 Ransburg July 27, 1954 2,723,646 Ransburg Nov. 15, 19552,733,172 Brennan Jan. 31, 1956 2,805,642 Tuttle et al. Sept. 10, 1957Notice of Adverse Deszision in Interference In Interference No. 91,630involving Patent N 0. 2,933,414, L. Beck, Electrostatic spray paintingmethod and apparatus, final decision adverse to the patentee wasrendered. Feb. :21, 1963, as to claim 1.

[Ofiicz'al Gazette July 23, 1.963.]

1. THE METHOD OF ELECTROSTATICALLY PAINTING ARTICLES WHICH COMPRISESPROJECTING A THIN STREAM OF PAINT SUBSTANTIALLY FREE OF ADMIXTURE WITHAIR OR OTHER GAS AND AT A HIGH PRESSURE THROUGH A NOZZLE AND AGAINST ASTRIKE PLATE DISPOSED IN THE PATH OF THE STREAM BUT AT AN ANGLE TO SAIDPATH, WHEREBY THE PAINT, AFTER STRIKING THE PLATE IS DEFLECTED AT THEPOINT OF IMPINGEMENT IN A DIRECTION ANGULAR TO THE DIRECTION OF SAIDSTREAM, AND IS BROKEN UP INTO PARTICLES FORMING A FOG-LIKE VAPOR, ANDCAUSING SAID VAPOR TO PASS THROUGH AN ELECTROSTATIC ZONE BETWEEN SAIDSTRIKE PLATE AND SAID ARTICLES, TO COAT SAID ARTICLES.